Supplementary Planning Document: Biodiversity Net Gain

The Council will aim to conserve and enhance biodiversity within the District. In particular:

• the Council will work with its partners to protect and enhance legally protected species and all sites and networks of habitats of international, national, regional or local importance for wildlife or geology. development proposals should protect biodiversity
• provide for the long-term management, enhancement, restoration and, if possible, expansion of biodiversity, by aiming to restore or create suitable semi-natural habitats and ecological networks to sustain wildlife. This will be in accordance with the Buckinghamshire Biodiversity Action Plan as well as the aims of the Biodiversity Opportunity Areas and the Chiltern AONB Management Plan
• where development proposals are permitted, provision will be made to safeguard and where possible enhance any ecological interest
• where, in exceptional circumstances, development outweighs any adverse effect upon the biodiversity of the site and there are no reasonable alternative sites available, replacement habitat of higher quality will be provided through mitigation and/or compensation to achieve a net gain in biodiversity

The highest priority will be given to the conservation and enhancement of the natural beauty of the Chilterns Area of Outstanding Natural Beauty, and the integrity of Burnham Beeches Special Area of Conservation.

The conservation and enhancement of the Chilterns AONB and its setting will be achieved by ensuring that all development complies with the purposes of the AONB and its Management Plan. The conservation and enhancement of Burnham Beeches SAC, and its surrounding supporting biodiversity resources, will be achieved through restricting the amount of development in close proximity to the site, and ensuring that development causes no adverse effect on the integrity of the SAC. Further details on mechanisms for achieving this will be given in the Development Management DPD.

More generally, the landscape characteristics and biodiversity resources within South Bucks will be conserved and enhanced by:

• not permitting new development that would harm landscape character or nature conservation interests, unless the importance of the development outweighs the harm caused, the Council is satisfied that the development cannot reasonably be located on an alternative site that would result in less or no harm and appropriate mitigation or compensation is provided, resulting in a net gain in Biodiversity
• seeking the conservation, enhancement and net gain in local biodiversity resources within the Biodiversity Opportunity Areas, on other non-designated land, on rivers and their associated habitats, and as part of development proposals
• maintaining existing ecological corridors and avoiding habitat fragmentation
• conserving and enhancing landscapes, informed by Green Infrastructure Plans and the District Council’s Landscape Character Assessment
• improving the rural/urban fringe by supporting and implementing initiatives in the Colne Valley Park Action Plan
• seeking biodiversity, recreational, leisure and amenity improvements for the River Thames setting where opportunities arise, for example at Mill Lane (see Core Policy 15)

Provision will be made for new infrastructure to support growth, through planning obligations, the Community Infrastructure Levy (CIL) and other available funding streams as appropriate. Where justified, development will be required to provide or contribute towards delivering the key infrastructure requirements for the District including:

• environment
• green infrastructure – including landscape, recreation, and biodiversity improvements

The Council will promote the conservation and enhancement of the natural environment and green infrastructure of the District through:

Conserving, protecting and enhancing the Chilterns Area of Outstanding Natural Beauty and other natural environmental assets of local, national and international importance by:

• protecting them from harmful development through development management policies in this Plan and the Delivery and Site Allocations Plan including the protection of biodiversity and landscape designations and landscape character based approach to considering proposals
• working with the Chilterns AONB Board and other agencies to improve the management of the AONB and other natural assets, and help people’s enjoyment of them
• taking a landscape character-based approach to considering proposals

Ensuring there is a net gain in biodiversity within individual development proposals and across the District as a whole over the plan period.

Working with local natural environment partnerships to protect and enhance the green infrastructure network of the District by:

• protecting designated sites and through management plans ensuring their biodiversity value will be enhanced
• proactive, early and strategic planning of green infrastructure to maximise its benefits, including a baseline assessment of what exists (function, location, size, connectivity)
• keeping under review and updating the extent of the Green Infrastructure network in coordination with the Bucks and Milton Keynes Natural Environment Partnership and other agencies
• ensuring through development management policies that all development is required to maximise the opportunities to protect, enhance, expand, connect, improve and use the existing green infrastructure, including across the border of the development site

Working in partnership with the Environment Agency, Natural England and the water companies to protect, manage and improve water quality in the District, particularly the quality of water bodies which are currently failing to meet the Water Framework Directive (WFD) requirements as set out in the Thames River Basin Management Plan (RBMP).

All development is required to protect and enhance both biodiversity and green infrastructure features and networks both on and off-site for the lifetime of the development.

Development proposals are required to evidence a thorough understanding of context through the preparation of a proportionate assessment of existing and planned green infrastructure, biodiversity and ecological features and networks both on the site and in the locality, and demonstrate how, through physical alterations and a management plan for the lifetime of the development:

• existing green infrastructure and biodiversity assets will be maximised
• opportunities to enhance existing and provide new green infrastructure and biodiversity assets will be maximised
• development will deliver long lasting measurable net gains in biodiversity
• where appropriate, a monitoring plan will be put in place to review delivery of i - iii

And demonstrate how the mitigation hierarchy has been applied by following a sequential approach to avoid, minimise, mitigate, and finally compensate for (on then off-site) any harm to biodiversity. If significant harm cannot be avoided in this way, development will not be permitted.

Development (excluding householder applications) is required as a minimum to:

• secure adequate buffers to valuable habitats
• achieve a future canopy cover of 25% of the site area on sites outside of the town centres and 0.5 ha or more. This will principally be achieved through retention and planting of trees, but where it can be demonstrated that this is impractical the use of other green infrastructure (such as green roofs and walls) can be used to deliver equivalent benefit
• within town centres and on sites below 0.5 ha development is required to maximise the opportunities available for canopy cover (including not only tree planting but also the use of green roofs and green walls)
• make provision for the long-term management and maintenance of green infrastructure and biodiversity assets
• protect trees to be retained through site layout and during construction

1. All development proposals should be designed to maximise biodiversity by conserving, enhancing or extending existing resources or creating new areas or features.
2. Where potential biodiversity interest is identified on a site or the development creates an opportunity to increase biodiversity, the Council will require an ecological survey and report to be submitted which demonstrates how this will be addressed.

Internationally or nationally important Protected Sites (SACs and SSSIs) and species will be protected. Avoidance of likely significant adverse effects should be the first option. Development likely to affect the Chiltern Beechwoods SAC will be subject to assessment under the Habitat Regulations and will not be permitted unless any significant adverse effects can be fully mitigated.

Development proposals that would lead to an individual or cumulative adverse impact on an internationally or nationally important Protected Site or species, such as SSSIs or irreplaceable habitats such as ancient woodland or ancient trees, will be refused unless exceptional circumstances can be demonstrated as follows:

Sufficient information must be provided for the council to assess the significance of the impact against the importance of the Protected Site and its component habitats and the species which depend upon it. This will include the area around the Protected Site and the ecosystem services it provides and evidence that the development has followed the mitigation hierarchy set out below.

Protection and enhancement of biodiversity and geodiversity will be achieved by the following:

1. 1. a net gain in biodiversity on minor and major developments will be sought by protecting, managing, enhancing and extending existing biodiversity resources, and by creating new biodiversity resources. These gains must be measurable using best practice in biodiversity and green infrastructure accounting and in accordance with any methodology (including a Biodiversity Impact Assessment) to be set out in the Buckinghamshire Biodiversity Accounting SPD
      
   2. if significant harm to biodiversity resulting from a development cannot be avoided (through locating on an alternative site with less harmful impacts), adequately mitigated, or as a last resort, compensated for, then development will not be permitted. If a net loss in biodiversity is calculated, using a suitable Biodiversity Impact Assessment (see point 1) then avoidance, mitigation and compensation, on site first, then offsite must be sought so the development results in a net gain (percentage of net gain to meet any nationally set minimum standard and or as detailed in an SPD) in order for development to be permitted. Mitigation, compensation and enhancement measures must be secured and should be maintained in perpetuity. These assessments must be undertaken in accordance with nationally accepted standards and guidance (BS 8683 Biodiversity net gain in project design and construction; and CIRIA Biodiversity Net Gain Good practice principles for development)
      
   3. development which would result in damage to or loss of a site of biodiversity or geological value of regional or local importance (such as Local Wildlife Sites or Local Geological Sites) including habitats of principal importance (known as Priority Habitats) or the habitats of species of principal importance (Priority Species) or their habitats will not be permitted excepting exceptional circumstances where the need for, and benefits of the development significantly and demonstrably outweigh the harm it would cause to the site, and the loss can be mitigated and compensation provided to achieve a net gain
      
   4. the Council will, where appropriate, expect ecological surveys for planning applications. These must be undertaken by a suitably qualified person and consistent with nationally accepted standards and guidance (BS 42020: Biodiversity – Code of Practice for planning and development, and CIEEM Ecological Report Writing guidance) as replaced
      
   5. where development proposals affect a Priority Habitat (As defined in the Buckinghamshire Biodiversity Action Plan or UK Biodiversity Action Plan and as listed in accordance with s41 of the NERC Act 2006) then mitigation should not be off-site. Where no Priority Habitat is involved then mitigation is expected to follow the mitigation hierarchy, where options for avoidance, mitigation and compensation on- site, and then offsite compensation, should be followed in that order as outlined in point 2. When there is a reasonable likelihood of the presence of protected or priority species or their habitats, development will not be permitted until it has been demonstrated that the proposed development will not result in adverse impacts on these species or their habitats. The only exception will be where the advantages of development to the protected site and the local community clearly outweigh the adverse impacts. In such a case, the council will consider the wider implications of any adverse impact to a protected site, such as its role in providing a vital wildlife corridor, mitigating flood risk or ensuring good water quality in a catchment
      
   6. development proposals will be expected to promote site permeability for wildlife and avoid the fragmentation of wildlife corridors, incorporating features to encourage biodiversity, and retain and where possible enhance existing features of nature conservation value on site. Existing ecological networks should be identified and maintained to avoid habitat fragmentation, and ecological corridors including water courses should form an essential component of green infrastructure provision in association with new development to ensure habitat connectivity
      
   7. planning conditions/obligations will be used to ensure net gains in biodiversity by helping to deliver the Buckinghamshire and Milton Keynes Biodiversity Action Plan targets in the biodiversity opportunity areas and other areas of local biodiversity priority. Where development is proposed within, or adjacent to, a biodiversity opportunity area, biodiversity surveys and a report will be required to identify constraints and opportunities for biodiversity enhancement. Development which would prevent the aims of a Biodiversity Opportunity Area from being achieved will not be permitted. Where there is potential for development, the design and layout of the development should secure biodiversity enhancement and the council will use planning conditions and obligations as needed to help achieve the aims of the biodiversity opportunity area. A monitoring and management plan will be required for biodiversity features on site to ensure their long-term suitable management (secured through planning condition or Section 106 agreement)
      
   8. development proposals adversely affecting a Local Nature Reserve will be considered on a case-by-case basis, according to the amount of information available about the site and its significance, relative to the type, scale and benefits of the development being proposed and any mitigation. Any mitigation strategy will need to include cooperation with the nature reserve managers

1. The metric does not change the protection afforded to biodiversity. Existing levels of protection afforded to protected species and habitats are not changed by use of this or any other metric. Statutory obligations will still need to be satisfied.
2. Biodiversity metric calculations can inform decision-making where application of the mitigation hierarchy and good practice principles conclude that compensation for habitat losses is justified.
3. The metric’s biodiversity units are only a proxy for biodiversity and should be treated as relative values. While it is underpinned by ecological evidence the units generated by the metric are only a proxy for biodiversity and, to be of practical use, it has been kept deliberately simple. The numerical values generated by the metric represent relative, not absolute, values.
4. The metric focuses on typical habitats and widespread species. Important or protected habitats and features should be given broader consideration. Protected and locally important species needs are not considered through the metric, they should be addressed through existing policy and legislation. Impacts on protected sites (such as SSSIs) and irreplaceable habitats are not adequately measured by this metric. They will require separate consideration which must comply with existing national and local policy and legislation. Data relating to these can be entered into the metric, so as to give an indicative picture of the biodiversity value of the habitats present on a site, but this should be supported by bespoke advice.
5. The metric design aims to encourage enhancement, not transformation, of the natural environment. Proper consideration should be given to the habitats being lost in favour of higher-scoring habitats, and whether the retention of less distinctive but well-established habitats may sometimes be a better option for local biodiversity. Habitat created to compensate for loss of natural or semi-natural habitat should be of the same broad habitat type (for example, new woodland to replace lost woodland) unless there is a good ecological reason to do otherwise (to restore a heathland habitat that was converted to woodland for timber in the past, for example).
6. The metric is designed to inform decisions, not to override expert opinion. Management interventions should be guided by appropriate expert ecological advice and not just the biodiversity unit outputs of the metric. Ecological principles still need to be applied to ensure that what is being proposed is realistic and deliverable based on local conditions (such as geology, hydrology and nutrient levels) and the complexity of future management requirements.
7. Compensation habitats should seek, where practical, to be local to the impact. They should aim to replicate the characteristics of the habitats that have been lost, taking account of the structure and species composition that give habitats their local distinctiveness. Where possible compensation habitats should contribute towards nature recovery in England by creating ‘more, bigger, better and joined up’ areas for biodiversity.
8. The metric does not enforce a mandatory minimum 1:1 habitat size ratio for losses and compensation but consideration should be given to maintaining habitat extent and habitat parcels of sufficient size for ecological function. A difference can occur because of a difference in quality between the habitat impacted and the compensation provided. For example, if a habitat of low distinctiveness is impacted and is compensated for by the creation of habitat of higher distinctiveness or better condition, the area needed to compensate for losses can potentially be less than the area impacted. However, consideration should be given to whether reducing the area or length of habitat provided as compensation is an appropriate outcome.

1. Species metric(s) are a distinct entity and an evaluation of 'species biodiversity units' must be kept separate in any 'account' of the effects of an intervention on biodiversity. You must not sum habitat and species units to derive a total biodiversity unit value.
2. Species metric(s) can be used as an additional source of information to complement information provided by biodiversity metric 3.0. It is important that the habitat-based metric is used as the primary tool for evaluating biodiversity change. Using a species metric in isolation can result in significant risk of net loss in biodiversity.
3. A species metric needs to be consistent with all key principles of the biodiversity metric 3.0, particularly the principle that the metric does not change the protection afforded to biodiversity (Principle 1).
4. The legal provisions that apply to protected species (and habitats) take precedence in designing and planning the approach used to mitigate or compensate for impacts on species. An acceptable design must satisfy these legal requirements, even if this does not result in the best possible biodiversity unit outcome (based on evaluation using the biodiversity metric 3.0).
5. It is acceptable for the same area of habitat to be separately scored using the biodiversity metric 3.0 and 1 or more species metrics. Because each metric describes the value of that habitat from a distinct perspective the corresponding outputs represent a different biodiversity currency' and must not be summed.

Clause 5.1:

Clause 6.2.12 - finalise BNG design outputs:

BNG Management and Monitoring Plan (MMP) (see 8.1):

Clause 7.6 - Biodiversity Net Gain Agreement:

Clause 8.1 - Implementation of the Management and Monitoring Plan (MMP):

Clause 8.2 - Monitoring:

Clause 8.3 Reporting

Clause 8.4 Record Management